In the early days of the electronic organ, wondrous tones were created by simple electronic tone generators and by mechanical-electrical transducers operating in conjunction with mechanical tone generators. The sounds produced by the early instruments were figuratively flat and both literally and figuratively monotonous. Performance of such electronic organs was substantially improved with the advent of LESLIE (trademark of CBS INC.) speaker systems which utilize rotating sound channels. The previously monotonous sounds became lively and bright by superimposing vibrato and tremolo upon the electrical impulses.
Various improvements and refinements have been made in connection with such acoustic pulsato systems. Some improvements involve chorus and ensemble effects to enhance the depth and breadth of the sound source to an extent such that the listener perceives spatial and reverberation effects characteristic of a large concert hall. In general, it has been necessary to utilize a plurality of spaced speaker systems in order to obtain good concert hall effects.
A system described in USA Pat. No. 3,083,606 to Don L. Bonham issued Apr. 2, 1963 and entitled ELECTRICAL MUSIC SYSTEM achieves the illusion of space by dividing an electrical signal into a plurality of channels and superimposing different electrical phase-shift or vibrato in each of the channels. Such or similar effects have heretofore been unobtainable by mechanical means alone.
An object of the present invention is to provide chorus and ensemble effects upon musical signals by a simple mechanical structure capable of compact accommodation in a single small cabinet.